Cloud cluster automatic detection method based on foundation cloud atlas

Abstract

The present invention discloses a cloud cluster automatic detection method based on a foundation cloud atlas. The cloud cluster automatic detection method comprises: an image feature space conversion step for normalizing a ratio of a blue channel value and a red channel value of each pixel point in the foundation cloud atlas to obtain an NBR value serving as a color feature value of the pixel point; extracting the pixel points (called uncertain pixel points) of which the NBR values are within the interval of [0, 0.3], and performing minimum cross-entropy calculation to obtain a segmentation threshold with the minimum cross entropy; and comparing the NBR value of each pixel point with the segmentation threshold, if the NBR value is less than the segmentation threshold, judging that the pixel point is cloud cluster, and otherwise, judging that the pixel point is blue sky, thereby achieving detection of the cloud cluster. By only calculating the minimum cross entropy of the uncertain pixel points to obtain the optimum segmentation threshold, the cloud cluster automatic detection method of the present invention can well solve the problem of segmentation threshold offset caused by rendering of a background for the color of the cloud cluster in the case of an extremely blue sky or an extremely bright sky, thereby greatly improving detection precision of the cloud cluster in the foundation cloud atlas under a complicated background.

Description

technical field [0001] The invention relates to the field of cloud automatic detection methods, in particular to a cloud automatic detection method based on ground-based cloud images. Background technique [0002] The formation and evolution of cloud clusters play an important role in regulating the radiation budget of the earth, and at the same time affect global climate change, so the observation of cloud clusters is of great significance. As people pay more attention to the utilization of renewable energy, solar energy resources have been applied in many aspects due to their cleanliness and convenience, and one of the important ways is solar power generation. The photovoltaic power of the sun to the ground is mainly affected by cloud cover, so the observation of local cloud clusters has received more and more attention. The traditional observation of clouds mainly relies on meteorological satellites and human eye observations: satellite cloud images provide meteorologica...

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Problems solved by technology

But in fact, due to the complex changes of cloud and sky features, the images corresponding to many unimodal feature histograms may contain both cloud and sky elements at the same time, and there is no one between the two types of feature histograms. Very clear boundaries, so it is difficult to effectively solve the problem

[0015] In the limited threshold method, if the threshold obtained by the adaptive threshold method is not within the limited range, a boundary threshold is mechanically assigned. Although the newly obtained threshold is better than the threshold outside the limited range, it is usually not necessarily the most suitable and may still be misclassified. larger portion of elements

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